Modern Ways To Waterproof Construction, Foundation Using DPM & Other Methods For Effective Moisture Control

Foundation is that part of a building or structure that is below ground level, up to the over-site concrete slab level.

Adequate waterproofing of your foundation will result in a dry and safe below-grade environment.

There are certain foundation waterproofing best practices to ensure your waterproofing membrane is applied correctly and to ensure there is no water leakages and that there are no damages as a result of water leakages.

DPM short for Damp Proof Membrane, is commonly used to waterproof foundations in constructions.

So what is the proper way to use a DPM?

For a site where hard core is not utilized, proper way to apply the DPM is thus:

– Sand fill and compact.

– Lay double ply polythene sheets with over lappings not less than 150mm at the edges. Let the loose end of it flow over all the foundation beams.

– Do a blinding of cement & sand screed of ratio 1 : 6 all over the laid DPM to a thickness of 50mm.

It is on that 50mm screed that your grade reinforcements or mesh will be laid.

For a site where hardcore is utilized, the following is the approach to apply a DPM:

– After sand filling and compaction lay the hardcore.

– Use laterite to blind sharp surfaces of hardcore top.

– Lay your double ply polythene sheets with not less than 150mm over lappings at the edges. Let loose end of it flow over all beams in the foundation.

– Do a blinding of cement-sand screed of ratio 1 : 6 all over the laid DPM (nylon)

It is on that 50mm screed that your reinforcements will be assembled

DPMs alone nowadays are usually not efficient to cater for foundations moisture problems expecially where there is high moisture content and high water table.

This is why it is important to follow effective construction principles, like why laying your DPM. 

As stated above, there should be a minimum of 150mm over lap between DPM nylon materials.

If moisture situation requires, the DPM should be doubled to provide efficient moisture control as lower quality DPM polythenes are what we find in markets these days.

These brings to mind the need to effectively treat our reinforcements with epoxy coating if we want to cater for moisture problems efficiently.

Concrete should be treated for water penetration during casting or few days after in order to prevent water penetrating through the concrete to damage the rebars.

While concrete provides compressive strength to the structure, it is also pertinent to note that rebars provide structural integrity and tensile resistance to the structure as a whole. 

Concrete also helps to protect rebars hence the need for concrete covers for structural members.

We should therefore aim firstly, to prevent water from penetrating through the concrete to affect our reinforcements, and secondly, seek out ways to protect rebars from moisture damage even if they are touched by water.

This is why large modern construction companies make use of epoxy coated rebars for bridge constructions because the coating also protects corrosion of reinforcements.

You too can start taking charge of this approach to make your buildings more water tight.

Another very effective modern approach, is the application of internal waterproofing method.

Basically, there are two waterproofing methods used in construction viz, internal water proofing and external waterproofing.

You can read my post on internal and external waterproofing, which is better and cheaper here, for you to decide on which you should be using on your construction sites.

Key takeaways from this post include:

_ Endeavour to double your DPM polythene nylon (double-ply) rather than using single-ply during construction. DPMs manufactured prior to 1990s were of higher qualities than those being manufactured today. Making them double-ply, will cater for the loss in thickness synonymous with today’s Damp Proof Membranes.

_ Allow your DPMs to overlap at least at 150mm. This will prevent water ingress through the lapping joints.

_ Use epoxy coated reinforcements to provide more water resistance capabilities to your reinforcing steel bars.

While cutting corners can do the job, it is proper to do the right thing on construction sites. This will save you from the headaches and costs you will incur later to remedy the situation. It is usually more expensive to remedy a water damage to a structure than making adequate preparations at the construction stage.

Your reputation could be at stage for a bad job if you do not do the right thing now. So while economy and safety both matter in the construction sector, the structure should be safe before you consider to save cost because the cost you save today in doing a bad job, could be expended to remedy the situation tomorrow, or even lead to loss of lives. You definitely wouldn’t want that to happen would you?

So opt for the best at all times.

If you have been blessed by this post, don’t forget to share it with others to bless them too.